Concentration of ores by electromagnetic separation



March 9, 1937. ROWAND 2,072,907

CONCENTRATION OF ORES BY ELECTROMAGNETIC SEPARATION Filed Dec. 2, 1952 sSheets-Shet 1 INVENTOR fmsafiwnwo.

- ATTORNEYS March 9, 1937. L. G. ROWAND 7 CONCENTRATION OF ORES BYELECTROMAGNETIC SEPARATION Filed D ec 2, 1932' s Sheets-Sheet 2 7 Y JINVENTOR Len/As QJPOWA/VO.

ATI'ORN EYIS March 9, 1937. ROWAND 2,072,907

CONCENTRATION OF ORES BY ELECTROMAGNETIC SEPARATION Filed Dec. 2, 1952 5Sheets-Sheet 3 ATI'ORN EYS Patented Mar. 9. 1937 MAGNETIC SEPARATIONLewis G. Rowand, Brooklyn, N. Y.

Application December 2, 1932, Serial No. 645,459

which it is one of the objects of the present invention to eliminate.Another object of th'e present invention is to provide a method andapparatus which is operable with equal facility with all types andgrades of ores, minerals, residues and the like.

Another object of the present invention is to provide a method andapparatus which will yield 20 a selective concentration of magneticvalues with complex ores, minerals, residues and the like.

Still another object of the present invention is to provide a new methodand new type of apparatus for the electromagnetic separation of 5materials.

Other objects and advantages will become apparent as the invention ismore fully disclosed.

In accordance with the objects of the present invention I have devisedan improved method 30 of electromagnetically separating ores, minerals,residues and the like materials, in which the material is first groundto a particle size effective in separating the respective constituentsthereof from each other, and then made into a suitable 35 pulp orsuspension in a fluid medium. The thus obtained pulp is then fed in amtdesired manner into a column of fluid within which it may be suitablydispersed and the thus dispersed particles are allowed to pass throughan electromagnetic field projected across the fluid between two spacedwalls of the container therefor.

By suitable adjustment of the field strength of the electromagneticfield any desired magnetic separation of the particles may thus beefiected 45 and the ore particles not magnetically separated will passthrough the field and settle out in the bottom of the container. Whenthe magnetic field is concentrated upon a restricted area of thecontainer wall, the magnetically separated ma- 50 terial will collectthereon. By a proper design of the el'ectromagnet I have found that itis possible to laterally move the thus collected magnetic material alongthe container wall through the magnetic field towards a neutral pointthereof 55 whereby. a selective release of the magnetically All suchmethretained materials from the wall of the container can be effected.Thethus released magnetic material thereupon settles down to the bottomof the container and can be collected in separate compartments from theportion of the material not magnetically separated.

As a specific embodiment of the practice of the present invention I havedesigned one type of apparatus suitable for the practice of thedescribed method. Other types of apparatus may be designed, however, toeffectuate the same result. In the apparatus designed I have provided acontainer wherein a substantially quiescent body of fluid may beretained with a portion of said fluid extending as a column betweenspaced pole faces and a laterally movable armature spaced a determineddistance from the pole faces. Preferably the armature is rotatablelaterally between the pole faces. Means are provided to feed thematerial in pulp form into the column of fluid in such manner that itpasses through a magnetic field projected across the column of fluidbetween the pole faces and the armature. The armature face is designedso that the field flux concentration is at a plurality of pointsthereon. The magnetically attracted material collecting upon thecontainer wall adjacent the armature face is laterally moved therealongby the lateral movement of the armature through the electromagneticfield until the flux density is insufiicient to retain the material uponthe face of the container wall. The material then is released and fallsthrough the column of fluid intothe body of fluid wherein it iscollected in appropriate containers separate from the portion of thematerial that is not magnetically attracted.

Before further disclosing the nature and scope of the present inventionreference should be made to the accompanying drawings, wherein- Fig. 1 asectional side elevation view illustrating the broad inventive idea ofthe present invention schematically;

Fig. 2 is a sectional semi-schematic plan view of the same;

Fig. 3 is a plan view partly in section along plane 33 of Fig. 5 of onetype of apparatus designed to effectuate the present invention;

' Fig. 4 is a top view of the hopper and feed means of thesame;

Fig. 5 is a vertical cross-sectional elevation along plane 5-5, Fig. 3;

Fig. 6 is an enlarged sectional elevation of one of the features of thepresent invention;

Fig. '7 is an enlarged sectional plan view of the same.

Referring to the drawings, Fig. 1 illustrates schematically theoperating characteristics of the broad inventive idea of the presentinvention, and the remaining figures indicate one type of apparatus Ihave designed to effectuate the present invention. While the broad ideais generally applicable to all types of ores, minerals, residues and thelike which are susceptible to magnetic separation, for the purposes ofillustration and not as a limitation I will describe the apparatus andthe method as I have devised and adapted the same to the concentrationof materials containing magnetic iron constituents such as hematite,magnetite and the like. The magnetite is the most susceptible tomagnetic separation and the hematite is the least susceptible. As anexample of the practice of the present invention, the method andapparatus designed to operate upon oxidized iron ores in which the ironexists as hematite (F6203) and magnetite (F6304) with non-magneticgangue such as quartz, gneiss, schist, etc. or upon titaniferous ironores containing magnetite, ilmenite with quartz, schist, gneiss and thelike gangue materials will be described.

The ore is first ground to desired particle size adapted tosubstantially free the magnetic constitutents from the gangue ornon-magnetic constituents. This grinding may be done wet or dry.

The ore then may be screened or classified as desired to relativelyuniform particle sizes and made up into a pulp or suspension of anyconvenient or desired density and supplied in any convenient manner tohopper I. From hopper I the ore pulp is passed by valve 2 into feedfunnel 3 wherein it is admixed and further diluted with Water or othersuitable fluids as will hereinafter be defined before passing into aplurality of feed chutes 5 serving to carry the suspended ore par ticlesto the quiescent body of fluid 6 retained in container I. Container 1 ispreferably circular in shape as indicated in Figs. 3 and 5 and has aninner wall 8 concentric with the outer wall of the container 1 thusforming a core within which is disposed the electromagnet poles 9 andcore windings I 0 with a central opening II for air cooling. The facesof the poles 9 are positioned adjacent the core facepf inner wall 8 ofcontainer 1 at a distance below the surface of the body of quiescentfluid 6. The plurality of chutes 5 are identical in number to the numberof poles 9 and are positioned above the container 7 to bring thedischarge outlet at a point vertically above the said pole faces so thatin falling through the column of fluid retained between walls 8 and I3the ore particles must pass by the pole face.

A circular armature I2 is positioned in spaced relationship to the faceof poles 9 in a container having a side wall l3 closely contacting withthe face of the armature and an outer side wall l4 spaced from the outerwall of container 1 to provide for an overflow l5 substantially asindicated. The bottom l5 of the armature con tainer is spaced from thebottom of the container l to provide for a relatively large body ofsubstantially quiescent fluid. Means I6 is provided to rotate thearmature in a plane trans verse to the direction of fall at any desiredspeed. Poles 9 are substantially fixed and immovable except foradjustment. The inner face of armature I2 is pointed substantially asshown at I! to concentrate the magnetic flux thereon and is providedwith a plurality of vertical grooves to form teeth I8 to form pointsof-flux concentration thereon. The walls of fluid container I andarmature container l3 are preferably composed entirely of non-magneticmaterial, but the part of the container which lies within the magneticfield only is necessary to be non-magnetic.

As indicated in Fig. 5 as the ore particles fall substantiallyvertically down through the column of fluid between walls 8 and 13 themagnetic constituents thereof are drawn over to the container wall l3adjacent the face I! of armature I2 by the magnetic force of anelectromagnetic current circulating between the poles 9 and armature l2.The strength of this field is adjusted with respect to the precisespacing between the pole face and the armature and the magneticsusceptibility of the ore constituents it is desired to separate. In theseparating of hematite and magnetite from a single ore or admixture,when the spacing of the pole face and armature face approximatesone-half inch, the field strength should approximate the minimumstrength necessary to attract magnetically the hematite. This fieldstrength can be varied somewhat with respect to the particle size of thehematite and magnetite, and with the relative proportions of hematiteand magnetite in the ore, and with respect to the lateral distance it isdesired to carry the hematite by rotationof the armature. This fieldstrength also can be varied with respect to the magnetic permeabilitiesof the specific ores being treated.

After the magnetic materials are removed the non-magnetic materialscontinue to fall vertically into container l9 from which they'may beremoved through valve 20 as and when desired.

I have found. for example, that a field strength sufficient to effectthe separation of lowly magnetic hematite will be obtained by providingsufficient cross-sectional area in the core proportionate to thecross-sectional area in the pole and a suificient winding of the coil togive approximately 1000 ampere turns per square inch area of the core.

Upon a rotation of the armature l2 the magnetic material retained uponwall I3 is carried laterally a distance determined by the magneticsusceptibility and by the decreasing strength of the magnetic field asthe armature rotates between the poles. When the field strength lessensto such an extent that the material can no longer be retained upon thecontainer wall, it drops off as is indicated in Fig. 1. By the provisionof suitable hoppers 2| to 24 inclusive circumferentially disposed withincontainer 1 as indicated in Figs. 1 and 2, the falling magnetic materialmay be selectively collected into portions graded with respect to theirrelative magnetic susceptibilities.

Referring to Fig.2 the operation of this selective separation ofmagnetic materials may be readily recognized. The faces of poles 99 lieadjacent the container wall 8 and the face of armature l2 lies adjacentthe container wall 13. An. electromagnetic flux passes between the polesand the armature substantially as indicated by arrows. The point ofgreatest field strength is on the face of .the armature l2 opposite theface of each pole and the strength of the field decreases in eitherdirection towards the adjacent pole until at point N.S. a neutral pointis reached. At this point no magnetic material will be retained upon theface of wall I3.

When the armature is rotated the magnetic a point opposite pole face 9will follow the rotation of the armature due to the effects of theprogressivelyinto areas of decreasing field strength when the fieldstrength is not great enough to hold the material to the face of the 7wall I3 it will fall off and fall vertically down into appropriatehoppers 2i to 24 inclusive. The

'exact position of central point N.-S. will vary with respect to thespeed of rotation of armature I2 and as it'is desirable to prevent thevelocityof the magnetic material from carrying-thereleased materialcircumferentially over into the field of the succeeding magnet a bafileplate 25 is disposed substantially as shown to prevent the same. Thisbaflie can be ,made adjustable if desired.

In the separation of hematite and magnetite from ore residues and thelike, the hematite will be released first and be collected in one of thehoppers 2| to 23, depending upon the precise field strength conditions,and the magnetite having a magnetic susceptibility many times that ofhematite will ordinarilynot be released until it has been carried tonearly the neutral point and accordingly will be collected in the lasthopper 24. From these hoppers the materials may be withdrawn as and whendesired by valves 20.

In some types of ores the hematite and magnetite may be so closelyassociated as not to be completely freed from each other on grinding.Accordingly, middlings composed of admixtures of such unseparatedparticles will be obtained in one of the containers between 2| and 24.

In the specific embodiment herein shown, I have indicated four magnets.Instead of four magnets, I may employ only two or any multiple of two asdesired or as the size of the apparatus warrants.

In the preparation of a pulp or suspension, with some types of ores itmay be necessary to preferentially grind or to classify the ground oreinto suspensions of certain particle size ranges for optimum results. Itmay also be necessary to add to such suspensions colloid dispersionagents such as sodium silicate, etc. With some types of ores andresidues it may also be necessary to precondition the suspension by theaddition thereto oi dispersing agents such as acid or alkali tobeneflciate the settling properties of the ore particles in thequiescent body of fluid 6.-

It is contemplated within the scope of the present invention that thequiescent body of fluid 6 shall be comprised substantially of water. Tofacilitate the gravitational fall of ore particles through the body offluid, however, it is also contemplated that the specific gravity of thewater may be increased or decreased by the addition thereto of otherfluids, salts or chemical compounds. Thus for-example, for the purposesof the present invention I may use sea water, or

.artificial salt water, or I may add calcium chloride, or varioussulfate or alum compounds to the water for the purpose of changing thespecific gravity of the quiescent body of fluid 6. In such case theoverflow from I can be carried to a reservoir for conditioning andreturn to circuit, if desired, through diluting feed pipe 4. It is alsocontemplated that a continuous bottom discharge of fluid may benecessary in conjunction with overflow IE to maintain optimum conditionsin the device. Such bottom discharge means is indicated at 26.

It is also contemplated within the scope of the present invention thatthe viscosity of the quiescent body of fluid may be modified bycontrolling the temperature thereof in any convenient manner.

There are other features disclosed which may be widely varied withoutdeparting essentially from the nature and scope of the presentinvention. It ispreferable that chutes 5 should conduct the pulp orsuspension to the quiescent body of fluid 6 substantially in the mannershown so that the bulk of the falling ore particles pass relativelyclose to the face of the container wall adjacent the pole face toprovide for relatively 'clean'separation of the magnetic constituents.

Suitable baffle plates, sieves, screens, etc. may be employed tofacilitate this feature.

It is also contemplated that the pole faces of poles 9 and the adjacentcontainer wall 8 may be shaped to provide an inclined surface over whichthe falling ore particles may slide gravitationally through theelectromagnetic field. This arrangement will provide with any givenspacing of poles 9 and armature l2 a varying field strength for the oreparticles to pass through, thereby providing for a selective magneticseparation within the field. In this arrangement of elements thearmature I2 should be provided with a plurality of points of fluxconcentration I! positioned one above the other to facilitate theselective magnetic separation.

In the embodiment shown poles 9 and armature l2 are arbitrarily set afixed distance apart, and with this arrangement the magnetic separationis controlled by varying the strength of the magnetic fieldtherebetween. The exact spacing therebetween may be variable dependingupon contemplated service conditions and it is contemplated within thescope of the present invention that armature l2 and container l3therefor may be made as replaceable units, so that armatures of greateror lesser diameter may be employed thereby varying the spacing betweenthe pole face and the armature. While I have shown the armature movableand rotatable about the outer circumference of the apparatus it isapparent that it would involve no departure to reverse the poles and thearmature and to rotate the armature about the inner wall of thecontainer I.

Having broadly and specifically defined the present invention and theapparatus designed to effectuate the same, it is believed apparent thatmany modifications and departures may be made from the specificembodiment described herein without departing essentially from thenature and scope of the present invention as may be expressed andincluded within the following claims.

What I claim is:

1. Apparatus for the separation of materials comprising in combination,a container, a plurality of open compartments in the bottom of saidcontainer, at least one pair of electromagnetic poles disposed in spacedrelationship in a horizontal plane adjacent the outer face of one wallof said container, a movable armature disposed in substantially the samehorizontal plane adjacent the outer face of the opposite wall of saidcontainer, fluid filling said container, means to feed said material tothe surface of said fluid immediately above the space gaps between saidpoles and armature, means to move said armature in a horizontal planefrom one pole towards the other, and means to maintain the fluid levelin said container substantially constant.

2. Apparatus for the magnetic separation of materials including incombination, a vertical new p container being divided into a pluralityof separate compartments having valved outlet openings therein, fluidfilling said container, at least one pair of electr 'magnetic poles ofopposite polarity disposed a jacent the outer face of one wall of saidcontainer, said poles being disposed in spaced relationship insubstantially the same horizontal plane, a rotatable armature adjacentthe outer face of the opposite wall of said container in substantiallythe same horizontal plane, means to feed said material to the surface ofsaid fluid immediately above the space gaps between said poles and saidarmature, and means to maintain a substantially constant fluid level insaid container.

3. Apparatus for the magnetic separation of materials including incombination, a vertical hollow cylindrical container, the bottom of saidcontainer being divided into a plurality of separate compartments havingvalved outlet openings therein, fluid filling said container, aplurality of pairs of electromagnetic poles of opposite polaritydisposed adjacent the outer face of one wall of said container, saidpoles being disposed in spaced relationship in substantially the samehorizontal plane, a rotatable armature adjacent the outer face of theopposite wall of said container in substantially the same horizontalplane, means to feed said material to the surface of said fluidimmediately above the space gaps between said poles and said armature,and means to maintain a substantially constant fluid level in saidcontainer.

4. Apparatus for the magnetic separation of materials including incombination, a vertical hollow cylindrical container, the bottom of saidcontainer being divided into a plurality of separate compartments havingvalved outlet openings therein, fluid filling said container, at leastone pair of electromagnetic poles of opposite polarity disposed adjacentthe outer face of one wall of said container, said poles being disposedin spaced relationship in substantially the same horizontal plane, arotatable armature adjacent the outer face of the opposite wall of saidcontainer in substantially the same horizontal plane, means to feed saidmaterial to the surface of said fluid immediately above the space gapsbetween said poles and said armature, and means 0 to maintain asubstantially constantfluid level in said container and means toestablish a magnetic field of desired intensity between said poles andarmature.

5. Apparatus for the magnetic separation of materials including incombination, a vertical hollow cylindrical container, the bottom of saidcontainer being divided into a plurality of separate compartments havingvalved outlet openings therein, fluid filling said container, at leastone pair of electromagnetic poles of opposite polarity disposed adjacentthe outer face of one wall of said container, said polesbeing disposedin spaced relationship in substantially the same in said container, andmeans to establish a magnetic field of desired intensity between saidpoles and armature, and means to concentrate the lines of force of saidfield upon a plurality of points upon said armature.

6. The method of magnetically separating materials which comprisesdropping said material 1 through a column of fluid sustained in astationary receptacle enclosing the space gap between a horizontallymovable armature and a stationary electro-magnetic pole, therebyattracting the magnetical particles of said material to the inner faceof a wall of said receptacle next adjacent the said armature andhorizontally moving the same therealong to a point removed from the pathof fall of the non-magnetic particles of said material.

7. The method of magnetically separating materials which comprisesforming a suspension of said materials, incorporating therein aproportion of a reagent facilitating the segregation of magnetic fromnon-magnetic particles, dropping said material through a column of fluidsustained in a stationary receptacle enclosing the space gap between ahorizontally movable armature and a stationary electro-magnetic pole,thereby attracting the magnetic particles of said material to the innerface of a wall of said receptacle next adjacent the said armature andhorizontally moving the same therealong to a point removed from the pathof fall of the nonmagnetic particles of said material.

8. An electro-magnetic separator device comprising at least one pair ofelectro-magnetic poles disposed in horizontal spaced relation, anarmature horizontally movable disposed in horizontal bridging relationto said poles with a space gap therebetween, a stationary receptaclecontaining a fluid enclosing the said space gap, the side walls of saidreceptacle lying adjacent the faces of said armature and said poles, andmeans to drop a mixture of magnetic and non-magnetic particles throughthe said enclosed space gap whereby the said magnetic particles areseparated from the non-magnetic by being attracted to the inner face ofthe said wall next adjacent the said movable armature and carriedhorizontally therealong by movement of the said armature to a pointremoved from the path of fall of the said non-magnetic particles.

9. An electrc-magnetic separator device comprising at least one pair ofhorizontally spaced electro-magnetic poles of opposite polarity, anarmature movable horizontally and horizontally spaced from said poles, astationary receptacle containing a fluid disposed in the space gapbetween said poles and said armature and isolating the same from saidfluid and means to drop material comprising a mixture of magnetic andnon-magnetic particles through the said fluid within an electro-magneticfield passing between at least one of said poles and said armature,thereby attracting the said magnetic particles horizontal plane, arotatable armature adjcent/ t9 the inner face of the wall of saidreceptacle the outer face of the opposite wall of said con f a j ce th darmature d moving the tainer in substantially the same horizontal plane,means to feed said material to the surface of said fluid immediatelyabove the space gaps between said poles and said armature, and means tomaintain a substantially constantfluid level same horizontallytherealong out of the said magnetic field to a point removed from thepath of fall of said non-magnetic particles.

LEWIS G. ROWAND.

